The patient is a 57 year-old female who presented to her physician with an actively growing right neck mass that had been present for approximately six months. Additionally, she reported hoarseness and pain that radiated towards the back of her neck. She had a previous history of a goiter approximately 30 years ago, having undergone a left partial thyroidectomy in 1982. She denied ever having a history of hyper- or hypo-thyroidism. She denied any shortness of breath, chest pain, nausea, vomiting, or diarrhea.

Her past medical and surgical history is only significant for a cholecystectomy in 2012. She denied alcohol, tobacco, or illicit drug usage. She has a family history of ovarian cancer (sister).

On physical exam, she was noted to be in moderate distress, with a blood pressure of 152/94, heart rate of 68 beats per minute, and respiratory rate of 12 breaths per minute. She was noted to have a lateral deviation of her left eye. She had limited neck flexion due to the presence of the mass. Her cardiac, respiratory, abdominal, and neurological exams were otherwise unremarkable.

IMAGING STUDIES

A contrast-enhanced neck CT (Fig. 1) was preformed and revealed a marked asymmetric enlargement of the right lobe of the thyroid gland, measuring 11.5 cm x 10.6 cm x 7.8 cm. It was heterogenous in appearance, with areas of low attenuation, poorly or non-enhancing tissue, and some areas of calcification. There was leftward displacement of the airway and the right common carotid artery was displaced posteriorly and laterally over the margin of the mass. There was no definitive tracheal invasion.

CYTOLOGY

A fine needle aspiration was performed to further characterize the lesion. The patient's aspirate revealed a population of atypical spindle cells with pleomorphism, inconspicuous nucleoli, and coarse stippled chromatin. Immunohistochemical staining performed at an outside institution indicated that the spindle cell population stained positively for vimentin. A Ki-67 stain highlighted approximately 25% of the cells. A Congo Red stain was positive for amyloid. Although a calcitonin stain was not received for review, per the report from the outside institution, it was negative. The overall findings were suspicious for malignancy, with a specific suspicion for medullary thyroid carcinoma. The differential diagnosis also included Hurthle cell lesions, undifferentiated or poorly differentiated carcinomas of the thyroid, other spindle cell lesions of head and neck, and metastatic spindle cell tumors.

OPERATIVE

Given the concern for bleeding and potential airway invasion, the patient requested to have the lesion removed. A joint decision for operative management was made between the clinician and the patient and the patient underwent a total thyroidectomy. A right selective neck dissection was also performed at levels 2, 3, 4. There was no direct invasion of the carotids, but the jugular and vagus nerves were directly invaded and excised. The recurrent laryngeal nerve was also invaded by the lesion and was sacrificed with the total thyroidectomy.

The lesion was primarily sarcomatoid, with extensive necrosis throughout the thyroid parenchyma. An aggressive growth pattern was noted (Fig. 3). In an adjacent area to the primary pattern of the lesion, a well-differentiated papillary carcinoma was identified (Fig. 4). There were additionally bland areas with skenoid fibers and immunophenotypic myoid differentiation. Immunohistochemical stains for Cytokeratin AE1/AE3 (Fig. 5), Cam 5.2 (Fig. 6), and Pancytokeratin (Fig. 7) were focally positive in the sarcomatoid component of the lesion and strongly positive in the papillary thyroid carcinoma. P53 was strongly positive in the sarcomatoid component and weakly positive in the papillary thyroid carcinoma (Fig. 8). Actin (Fig. 9) and desmin (Fig. 10) had positive staining in the sarcomatoid component. TTF-1 (Fig. 11) and PAX8 (Fig. 12) were negative in the sarcomatoid component, but positive in the papillary thyroid carcinoma and normal thyroid gland tissue. Calcitonin, Synaptophysin, S100, Melan A, CD34, and Myogenin stains were negative in both components of the lesion.

MOLECULAR ANATOMIC PATHOLOGY

Mutations in BRAF, NRAS61, HRAS61, KRAS12/13, and RET/PTC1, RET/PTC3, and PAX8/PPARg rearrangements were not identified. Amplification of the GAPDH control was acceptable.

CLINICAL FOLLOW-UP

Information on the patient's clinical follow-up was not available at the time of case preparation.